1. Field of Invention
The inventions are directed to downhole valves for use in tool strings run into oil or gas wellbores and, in particular, to downhole valves that are capable of being opened and closed, while still permitting fluid flow through the downhole valve and, thus, through the tool string so that other downhole operations can be performed by devices located below the downhole valves.
2. Description of Art
Valves for use in downhole tools or to actuate downhole tools are generally known in the art. For example, valves are used to open and/or close passageways within downhole tools to direct fluid flow through the tool. Valves are also used in downhole tools, to open or close passageways from interior passageways within the downhole tool to the wellbore environment. In general, operation of these valves result in the closure of one passageway in favor of another passageway. As a result, fluid flowing through an original flow path is blocked while the fluid is flowing through the now opened secondary fluid flow path. One example of such a valve is a ball seat disposed in the bore of a downhole tool. Originally, fluid flow is permitted through the downhole tool by passing through the seat. A plug member, e.g., a ball, is then landed on the seat, thereby blocking the flow through the seat. The resultant build-up of pressure can actuate a downhole tool such as by causing shear screws to break, or, possibly, cause a rupture disk to break allowing the fluid to flow in one or more different directions, referred to herein as “secondary flow directions.” Flow through the seat, however, remains blocked so that no fluid flow is permitted to pass below the seat. In other words, any fluid actuated operations below the seat are “on hold” until the ball can be removed from the seat. In addition, simple removal of the ball to allow the flow to be re-established through the downhole tool does not close the now opened secondary flow directions, so that the valve is not a “full function valve” permitting opening and closing of the secondary flow directions.
In another example of a previous valve, the valve is run into the wellbore in the “opened” position, i.e., fluid is permitted to flow from the annulus of the wellbore, through the ports in the housing of the valve and up the bore of the tool string. After locating the tool string and, thus, the valve, in the wellbore, the valve is actuated to close the valve to the annulus so that flow is only permitted to pass out the bottom of the valve. The valve can be actuated a second time to re-open the housing ports to re-establish flow to the annulus. These types of valves are referred to as “dual action” valves and, although they permit fluid to flow through the valve and out the bottom of the valve when the valve is in both its opened and closed position, they are not capable of being run into the wellbore in the closed position, fully actuated, and retrieved out of the wellbore in the closed position.
To the inventors' knowledge, current operations of downhole valves are incapable of being run into the wellbore in a closed position, actuated to redirect flow above the seat while still allowing flow through the downhole tool to allow tools and devices located below the seat so that additional operations can be simultaneously performed below the seat, and subsequently be actuated to close the redirected flow path above the seat while still allow flow through the downhole tool to allow operations to be performed by tools and devices located below the seat.